Flexible packaging is used for many consumer goods, particularly food and beverages that are often packaged in pouches of flexible materials. The term “liquid-packaging” is understood by those skilled in the art to refer to both liquids and other flowable materials or product.
These packages are formed, filled, and sealed by a vertical form, fill, seal (“VFFS”) machine. Typically useful VFFS machines are shown in U.S. Pat. No. 4,947,621 and U.S. Pat. No. 6,182,426. However, commercially available VFFS machines pose a problem in that, to adjust its film heat sealing mechanism, their operation must be stopped. Such adjustments may be required, for example, when a different film is used; when the package requires another level of seal strength to compensate for the wear of parts of the heat sealing mechanism such as the heat sealing jaws; or when the pressure applied to the heat sealing jaws needs to be increased to form an adequate seal for the package. The present invention permits adjusting pressure applied by the heat sealing jaws without stopping the machine and without substantially losing any flexible packages being made.